The present invention relates to improvements in devices for driving nails in places where it is difficult to use an ordinary hammer.
There are many places where it is desirable to drive nails to hold structural members together, but where the proximity of objects which can be moved only with great difficulty makes it impossible to swing a hammer to drive the nails. For example, when assembling forms for pouring concrete it is often desirable to place nails in places where reinforcing bar material interferes with the ability to swing a hammer. Similarly, clearance is often limited above and below cabinets, making it difficult to drive nails which may be required to support the cabinets, or to attach moldings.
In other situations there is room enough to permit use of a hammer to drive nails, but proximity to finished surfaces may make it undesirable to use a conventional hammer.
In many situations the angle from which access is available to the location where a nail must be placed makes use of an ordinary hammer very awkward or difficult.
In yet other situations it is desirable to set nails below the level of the surrounding surface. For example, when installing gypsum wallboard, nails are commonly countersunk, and joints and nail holes are filled during finishing of a wall. Driving nails below the surface plane of a sheet of wallboard requires use of a nail set, ordinarily, in addition to a hammer.
In the past one way of installing nails in such difficult places has been to use as a guide a slender tube whose interior size permits a nail to slide through the tube, and to use a hammer to drive a rod which fits slidably within the tube and is held against the head of the nail. Use of such a tube and rod combination makes it possible to drive nails in otherwise inaccessible or awkward locations. It is difficult, however, to use the tube, rod, and hammer combination safely in overhead locations. There, the rod is likely to slide out of position unless it is held by the user, and holding the rod creates a risk of pinching the user's fingers between the rod and the guiding tube.
Another previously known device for driving nails in awkward or inaccessible locations is a combination of a tube and a rod slidable through the tube to drive against the head of a nail, the rod having a spherical handle at one end. While such a device is an improvement over driving the rod with an ordinary hammer, the combined weight of the rod and spherical handle of the available tools of this type is too small for effectively driving nails. Also, the tool is still subject to the disadvantage of the previously known combination, in that it is easily possible to pinch the user's fingers between the rod and the tube, or between the ball and the tube. Additionally, there is no gauge provided for countersinking a nail to any predetermined depth.
What is desired, then, is an improved device which can be used to drive nails in locations where it is difficult or impossible to drive nails using a hammer. Such a tool should include provisions to prevent the user from pinching himself during use of the tool and should preferably provide a capability to countersink nails to a predetermined depth.